This invention concerns a device to retrieve and discharge short bars.
The bars with which the invention is concerned are rolled or drawn bars sheared to size, which are conveyed on a conveyor means to a packaging station.
The device to retrieve and discharge short bars according to the invention is employed in cooperation with bar feeder means such as conveyor chains, for instance, so as to retrieve and discharge, upstream of the counting and separation zone, the bars which have a length shorter than the nominal pre-set length.
The state of the art covers the problem of retrieving and discharging short bars included in a plurality of bars being fed parallel and side by side on a conveyor chain means in a direction perpendicular to the lengthwise extent of the bars.
The especially important requirement in this field is to be able to extract the short bars from the plurality of bars without affecting or slowing down the output.
This means that the extraction has to be carried out on each occasion without stopping the feed of the layer of bars and without occupying the extraction station for too much time, for otherwise that station would not be productive.
The short bars have to be removed when they do not meet the requirements of a pre-set length and do not fall within the limits of an accepted dimensional tolerance.
These too short bars are removed so as to ensure the formation of homogeneous bundles consisting of bars all of which have a minimum length that complies with the specified requirements.
The state of the art contains a solution whereby the short bars are removed during their forward feed on substantially horizontal conveyor chains by including at a given determined point in those conveyor chains a separation channel having its axis parallel to the axis of the bars being fed and therefore substantially perpendicular to the direction of feed of the bars.
Bridge-type supporting means are fitted at the separation channel and are spaced apart transversely and extend lengthwise so as to straddle the separation channel completely.
The transverse gap between the supporting means is such that the bars having a length greater than the required minimum rest with their ends on the supporting means, which are associated with chain means that ensure the onward feed of the bars.
The bars which do not reach the pre-set minimum length fall when they reach the separation channel since they are no longer upheld by the conveyor chains or by the supporting means.
This system entails the problem that the bars which have an adequate length but a thin cross-section and which are upheld only at their ends by the supporting means bend at their central portion and create problems when they should be cooperating with feeder means located downstream of the separation channel.